U.S. patent application number 11/410015 was filed with the patent office on 2006-11-09 for blood pressure meter using viscoelasticity of cuff and mobile terminal having the same.
This patent application is currently assigned to SAMSUNG ELECTRONICS CO., LTD.. Invention is credited to Hyouk-ryeol Choi, Ki-wang Kim, Kyung-ho Kim, Ja-choon Koo, Sang-hoon Shin.
Application Number | 20060253041 11/410015 |
Document ID | / |
Family ID | 37394948 |
Filed Date | 2006-11-09 |
United States Patent
Application |
20060253041 |
Kind Code |
A1 |
Shin; Sang-hoon ; et
al. |
November 9, 2006 |
Blood pressure meter using viscoelasticity of cuff and mobile
terminal having the same
Abstract
A blood pressure meter using a viscoelastic cuff, and a mobile
terminal having the blood pressure meter. The blood pressure meter
includes a blood pressure sensor for measuring variation in blood
pressure, a blood flow sensor for measuring variation in blood
flow, a cuff that elastically compresses a body part and
decompresses the body part due to its viscoelasticity, and a
control unit that analyzes signals measured by the blood pressure
sensor and the blood flow sensor and calculates blood pressure. The
blood pressure meter is detachably connected to a mobile terminal
body, and can be small and portable. It is possible to measure the
blood pressure precisely even when the cuff is fitted onto a
finger, thereby improving the reliability of the blood pressure
measurement. By using the viscoelasticity of the cuff and auxiliary
decompressing, it is possible to check the blood pressure at all
times.
Inventors: |
Shin; Sang-hoon;
(Seongnam-si, KR) ; Choi; Hyouk-ryeol; (Gunpo-si,
KR) ; Koo; Ja-choon; (Seoul, KR) ; Kim;
Kyung-ho; (Yongin-si, KR) ; Kim; Ki-wang;
(Seoul, KR) |
Correspondence
Address: |
SUGHRUE MION, PLLC
2100 PENNSYLVANIA AVENUE, N.W.
SUITE 800
WASHINGTON
DC
20037
US
|
Assignee: |
SAMSUNG ELECTRONICS CO.,
LTD.
|
Family ID: |
37394948 |
Appl. No.: |
11/410015 |
Filed: |
April 25, 2006 |
Current U.S.
Class: |
600/493 ;
600/490 |
Current CPC
Class: |
A61B 5/02241 20130101;
A61B 5/02225 20130101; A61B 5/02208 20130101; A61B 5/02233
20130101 |
Class at
Publication: |
600/493 ;
600/490 |
International
Class: |
A61B 5/02 20060101
A61B005/02 |
Foreign Application Data
Date |
Code |
Application Number |
May 3, 2005 |
KR |
10-2005-0037048 |
Claims
1. A blood pressure meter comprising: a pressure adjusting member
comprising a cuff that is elastically deformed at a time of fitting
the cuff onto a body part of a testee to compress the body part and
impede blood flow, and whose compressing pressure to the body part
is decreased over time due to its viscoelasticity; a blood pressure
sensor that measures the pressure of the body part at a time of
compression and decompression of the pressure adjusting member; and
a control unit that analyzes a signal measured by the blood
pressure sensor at the time of compression and decompression of the
pressure adjusting member and calculates the blood pressure of the
testee.
2. The blood pressure meter according to claim 1, further
comprising a blood flow sensor that measures variation in blood
flow, wherein the control unit analyzes the signal measured by the
blood pressure sensor and a signal measured by the blood flow
sensor at the time of compression and decompression of the pressure
adjusting member and calculates the blood pressure of the
testee.
3. The blood pressure meter according to claim 2, wherein the blood
flow sensor includes a sound pressure sensor that measures a
Korotkoff sound, and wherein the control unit calculates the blood
pressure of the testee using a Korotkoff measuring method.
4. The blood pressure meter according to claim 2, wherein the blood
flow sensor includes first, second, third, and fourth terminals
that sequentially come into contact with the body part in a blood
flow direction, and wherein a variation in an impedance of the body
part due to a variation in blood flow is measured by applying a
reference voltage across the first and fourth terminals and
measuring a voltage across the second and third terminals.
5. The blood pressure meter according to claim 4, wherein the
control unit checks whether the blood flow is blocked at the time
of compression of the pressure adjusting member by using the blood
flow sensor, captures the time point when the blood flow resumes at
the time of decompression of the pressure adjusting member by using
the blood flow sensor, and calculates the signal measured by the
blood pressure sensor at the time point when the blood flow
resumes, to find the systolic pressure.
6. The blood pressure meter according to claim 4, wherein the
pressure adjusting member further includes a cuff fitting member
having first and second pieces with lockers provided at one end of
each piece, and of which the other ends are coupled to each other
with a hinge member, and wherein the first and second pieces are
locked to each other through the lockers at the time of fitting the
cuff and the first and second pieces are unlocked and opened about
the hinge member at the time of removing the cuff.
7. The blood pressure meter according to claim 6, wherein the
pressure adjusting member further includes a cuff interference
member that is rotatably provided in the cuff fitting member, that
contacts and interferes with the cuff in a direction in which it
comes in close contact with the body part at the initial time of
fitting the cuff, and that is rotated in the inversed direction
over time, and wherein the cuff interference member further
enhances the amount of decompression of the cuff.
8. The blood pressure meter according to claim 6, wherein the
pressure adjusting member further includes a cuff interference
member that is slidably provided in the cuff fitting member, that
contacts and interferes with the cuff in a direction in which it
comes in close contact with the body part at the initial time of
fitting the cuff, and that is slid in the inversed direction over
time, and wherein the cuff interference member further enhances the
amount of decompression of the cuff.
9. The blood pressure meter according to claim 6, wherein the cuff
is composed of a pair of bands, with one end fixed respectively to
the first and second pieces, and the other end free, wherein the
pressure adjusting member further includes: a cuff hole formed in
the hinge member so as to pass the free ends; and a cuff cam formed
in the hinge member so as to compress the free ends when the first
and second pieces are unlocked and release the free ends when the
first and second pieces are locked, and wherein the cuff hole and
the cuff cam further enhance the amount of decompression of the
cuff.
10. The blood pressure meter according to claim 4, wherein the
pressure adjusting member further includes an auxiliary
decompressing means for further enhancing the amount of
decompression of the cuff due to the viscoelasticity.
11. The blood pressure meter according to claim 4, wherein the cuff
is composed of a pair of bands, and one end of the cuff is free,
and wherein the pressure adjusting member further includes a cuff
fitting member that fixes the other end of the cuff; and a cuff
driving unit that pulls the free end so as to compress the body
part fitted with the cuff at the initial time of fitting the cuff,
and releases the free end over time so as to further enhance the
amount of decompression of the cuff.
12. The blood pressure meter according to claim 11, wherein the
cuff driving unit includes a cuff driving axis around which the
free end of the cuff is wound, and wherein the cuff driving unit
adjusts the compressing pressure and the decompressing pressure by
rotating the cuff driving axis.
13. The blood pressure meter according to claim 1, wherein the
pressure adjusting member further includes a cuff fitting member
having first and second pieces with lockers provided at one end of
each piece, and of which the other ends are coupled to each other
with a hinge member, and wherein the first and second pieces are
locked to each other through the lockers at the time of fitting the
cuff, and the first and second pieces are unlocked and opened about
the hinge member at the time of removing the cuff.
14. The blood pressure meter according to claim 13, wherein the
pressure adjusting member further includes a cuff interference
member that is rotatably provided in the cuff fitting member, that
contacts and interferes with the cuff in a direction in which it
comes in close contact with the body part at the initial time of
fitting the cuff, and that is rotated in the inversed direction
over time, and wherein the cuff interference member further
enhances the amount of decompression of the cuff.
15. The blood pressure meter according to claim 13, wherein the
pressure adjusting member further includes a cuff interference
member that is slidably provided in the cuff fitting member, that
contacts and interferes with the cuff in a direction in which it
comes in close contact with the body part at the initial time of
fitting the cuff, and that is slid in the inversed direction over
time, and wherein the cuff interference member further enhances the
amount of decompression of the cuff.
16. The blood pressure meter according to claim 13, wherein the
cuff is composed of a pair of bands, with one end fixed
respectively to the first and second pieces, and the other end
free, wherein the pressure adjusting member further includes: a
cuff hole formed in the hinge member so as to pass the free ends;
and a cuff cam formed in the hinge member so as to compress the
free ends when the first and second pieces are unlocked and release
the free ends when the first and second pieces are locked, and
wherein the cuff hole and the cuff cam further enhance the amount
of decompression of the cuff.
17. The blood pressure meter according to claim 1, wherein the
pressure adjusting member further includes an auxiliary
decompressing means for further enhancing the amount of
decompression of the cuff.
18. The blood pressure meter according to claim 1, wherein the cuff
is composed of a pair of bands, and one end of the cuff is free,
and wherein the pressure adjusting member further includes a cuff
fitting member that fixes the other end of the cuff; and a cuff
driving unit that pulls the free end so as to compress the body
part fitted with the cuff at the initial time of fitting the cuff,
and releases the free end over so as to further enhance the amount
of decompression of the cuff due to the viscoelasticity.
19. The blood pressure meter according to claim 18, wherein the
cuff driving unit includes a cuff driving axis around which the
free end of the cuff is wound, and wherein the cuff driving unit
adjusts the compressing pressure and the decompressing pressure by
rotating the cuff driving axis.
20. A mobile terminal having a blood pressure meter, the mobile
terminal comprising: a mobile terminal body having a display unit
that displays a measured blood pressure; and a blood pressure
measuring unit that measures blood pressure and is connected to the
mobile terminal body, wherein the blood pressure measuring unit
includes: a pressure adjusting member comprising a cuff that is
elastically deformed at the time of fitting the cuff onto a body
part of a testee to compress the body part and impede blood flow,
and whose compressing pressure to the body part is decreased due to
its viscoelasticity over time; a blood pressure sensor that
measures the pressure of the body part at a time of compression and
decompression of the pressure adjusting member; a blood flow sensor
that measures variation in blood flow; and a control unit that
analyzes the signal measured by the blood pressure sensor and a
signal measured by the blood flow sensor at the time of compression
and decompression of the pressure adjusting member and calculates
the blood pressure of the testee.
Description
CROSS-REFERENCE TO RELATED PATENT APPLICATION
[0001] This application claims the benefit of Korean Patent
Application No. 10-2005-0037048, filed on May 3, 2005, in the
Korean Intellectual Property Office, the disclosure of which is
incorporated herein in its entirety by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a blood pressure meter and
a mobile terminal having the blood pressure meter and, more
particularly, to a blood pressure meter made more portable by
simplifying the structure of a cuff for compressing or
decompressing a body part of a testee, and a mobile terminal having
the blood pressure meter.
[0004] 2. Description of the Related Art
[0005] Blood pressure is classified into arterial pressure,
capillary pressure, and venous pressure, but the term is usually
used to refer to arterial pressure. Arterial pressure varies during
each heartbeat. The blood pressure when a ventricle of the heart
contracts and pushes blood out to an artery is referred to as
systolic pressure. The systolic pressure is the maximum blood
pressure in the blood vessels. When the ventricle of the heart
expands and does not push blood out, the artery walls are elastic
and maintain some blood pressure. This pressure is referred to as
diastolic pressure. The diastolic pressure is the minimum blood
pressure. The difference between the systolic pressure and the
diastolic pressure is referred to as the pulse pressure.
[0006] Blood pressure varies depending on the conditions.
Accordingly, it is difficult to clearly determine blood pressure
with one measurement. The blood pressure measured on an empty
stomach right after waking is referred to as basic pressure. The
basic pressure is helpful for medical diagnosis. In real life, it
is necessary to measure the blood pressure several times under
various conditions. Therefore, there is a need for a portable
electronic blood pressure meter which can be handled at home by
general users.
[0007] An apparatus which can keep a constant contact area between
a finger and a cuff regardless of the thickness of the finger is
disclosed in U.S. Pat. No. 5,511,551, entitled "Cuff for blood
pressure meter." A foldable cuff is disclosed in U.S. Pat. No.
5,807,266, entitled "Finger-type Blood Pressure Meter with a
Flexible Foldable Finger Cuff." An apparatus which can bring a cuff
into close contact with a finger by manually pulling the cuff is
disclosed in U.S. Pat. No. 5,119,823, entitled "Cuff Wrapping
Apparatus for Blood Pressure Meter."
[0008] The above-mentioned patent inventions have a common feature
that a cuff is fitted onto a finger and compressed or decompressed
with air pressure. However, since a volume of air must be injected
into the cuff in order to finely adjust the pressure of the cuff,
the size of the cuff is increased. Miniature air-pressure cuffs are
possible but are not capable of precise decompression for measuring
blood pressure. In addition, mechanical parts such as a pump, a
drive source, and a valve, for adjusting the pressure of the cuff,
hinder the decrease in size of the blood pressure meter. On the
other hand, in order to check blood pressure for health care at all
times, the portability of the blood pressure meter should be
improved. Therefore, there is a need for a small, lightweight blood
pressure meter having a simple cuff which can replace the
air-pressure cuff.
SUMMARY OF THE INVENTION
[0009] The present invention provides a blood pressure meter having
a cuff with a simple structure which can replace a conventional
air-pressure cuff, to decrease the size and improve the portability
of the blood pressure meter, and a mobile terminal having the blood
pressure meter.
[0010] According to an aspect of the present invention, there is
provided a blood pressure meter comprising: a pressure adjusting
member including a cuff that is elastically deformed at the time of
fitting the cuff onto a body part of a testee to compress the body
part and impede blood flow, and whose compressing pressure to the
body part is decreased due to its viscoelasticity over time; a
blood pressure sensor that measures the pressure of the body part
at the time of compression and decompression of the pressure
adjusting member; and a control unit that analyzes a signal
measured by the blood pressure sensor at the time of compression
and decompression of the pressure adjusting member and calculates
the blood pressure of the testee.
[0011] The blood pressure meter according to the present invention
may further comprise a blood flow sensor for measuring variation in
blood flow. Here, the control unit may analyze signals measured by
the blood pressure sensor and the blood flow sensor at the time of
compression and decompression of the pressure adjusting member and
may calculate the blood pressure of the testee.
[0012] According to another aspect of the present invention, there
is provided a mobile terminal having a blood pressure meter, the
mobile terminal comprising: a mobile terminal body having a display
unit for displaying the measured blood pressure; and a blood
pressure measuring unit that measures blood pressure and is
connected to the mobile terminal body. Here, the blood pressure
measuring unit includes: a pressure adjusting member having a cuff
that is elastically deformed at the time of fitting the cuff onto a
body part of a testee to compress the body part and impede blood
flow, and whose compressing pressure to the body part is decreased
due to its viscoelasticity over time; a blood pressure sensor that
measures the pressure of the body part at the time of compression
and decompression of the pressure adjusting member; a blood flow
sensor for measuring variation in blood flow; and a control unit
that analyzes signals measured by the blood pressure sensor and the
blood flow sensor at the time of compression and decompression of
the pressure adjusting member and calculates the blood pressure of
the testee.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The above and other features and advantages of the present
invention will become more apparent by describing in detail
exemplary embodiments thereof with reference to the attached
drawings in which:
[0014] FIG. 1 is a graph illustrating a Korotkoff measuring method
in a blood pressure meter according to an exemplary embodiment of
the present invention;
[0015] FIG. 2 is a graph illustrating an oscillometric measuring
method in a blood pressure meter according to an exemplary
embodiment of the present invention;
[0016] FIGS. 3A and 3B are graphs illustrating viscoelasticity of a
cuff according to an exemplary embodiment of the present
invention;
[0017] FIG. 4A is a perspective view illustrating a cuff of the
blood pressure meter according to an exemplary embodiment of the
present invention before fitting the cuff, and FIG. 4B is a plan
view illustrating the cuff after fitting the cuff;
[0018] FIG. 5A is a plan view illustrating a cuff interference
member according to an exemplary embodiment of the present
invention before fitting the cuff, and FIG. 5B is a plan view
illustrating the cuff interference member after fitting the
cuff;
[0019] FIG. 6A is a plan view illustrating a cuff interference
member according to another exemplary embodiment of the present
invention before fitting the cuff, and FIG. 6B is a plan view
illustrating the cuff interference member after fitting the
cuff;
[0020] FIG. 7A is a plan view illustrating a cuff interference
member according to another exemplary embodiment of the present
invention before fitting the cuff, and FIG. 7B is a plan view
illustrating the cuff interference member after fitting the
cuff;
[0021] FIG. 8 is a plan view illustrating an exemplary embodiment
of a cuff driving unit according to the present invention;
[0022] FIG. 9A is a perspective view illustrating an impedance
measurement principle of a blood flow sensor according to an
exemplary embodiment of the present invention, FIG. 9B is a partial
perspective view of the cuff fitted with the blood flow sensor, and
FIG. 9C is a graph illustrating the voltage across second and third
terminals;
[0023] FIG. 10 is a block diagram illustrating a mobile terminal
having the blood pressure meter according to an exemplary
embodiment of the present invention; and
[0024] FIG. 11 is a perspective view illustrating a mobile terminal
having the blood pressure meter according to an exemplary
embodiment of the present invention.
DETAILED DESCRIPTION OF ILLUSTRATIVE, NON-LIMITING EMBODIMENTS OF
THE INVENTION
[0025] Hereinafter, exemplary embodiments of the present invention
will be described in detail with reference to the accompanying
drawings. The exemplary embodiments of the present invention are
not limited to the attached drawings, but may be modified in form
without departing from the scope of the present invention.
[0026] The pressure in the blood vessel when blood in a ventricle
of a heart is sent out to a main artery by contraction of the heart
muscle is referred to as the systolic pressure or the maximum blood
pressure, and is usually about 120 mmHg. The pressure in the blood
vessel when the heart expands is referred to as the diastolic
pressure or the minimum blood pressure, and is usually about 80
mmHg. Blood pressure measuring methods can be roughly classified
into direct measuring methods and indirect measuring methods. In a
direct measuring method, a catheter is inserted into the artery and
connected to a manometer or the like. Then, the pressure in the
artery is directly measured. Indirect measuring methods are further
classified into Korotkoff measuring methods, oscillometric
measuring methods, and Doppler ultrasonography measuring
methods.
[0027] In an exemplary embodiment of the present invention, a cuff
made of a viscoelastic material is used in place of an air-pressure
cuff. A pressure adjusting means according to an exemplary
embodiment of the present invention includes the cuff made of a
viscoelastic material.
[0028] According to an exemplary embodiment of the present
invention, the pressure adjusting means includes a cuff that is
elastically deformed at the time of fitting the cuff onto a body
part of a testee, to compress the body part to impede blood flow,
and whose compression decreases over time. The pressure adjusting
means compresses and decompresses the body part, and the blood
pressure is measured with a blood pressure sensor.
[0029] The blood pressure sensor may be coupled to or separated
from the cuff. The blood pressure sensor measures the pressure of
the cuff body part at the time of compression and decompression of
the pressure adjusting means. The blood pressure sensor may be a
contact type or a non-contact type. A blood pressure sensor that
can measure dynamic oscillation, such as an acceleration sensor,
may be suitably used for the oscillometric measuring method shown
in FIG. 2. The blood pressure sensor may directly output the
operational pressure by the blood pressure or may output the
operational pressure as a voltage. The blood pressure sensor can be
embodied in various forms, which are well known to those skilled in
the art, and detailed descriptions of which will be omitted.
[0030] According to an exemplary embodiment of the present
invention, the blood pressure sensor is provided on a contact
surface between the cuff and the body part, and measures variations
in contact pressure between the cuff and the body part. The control
unit controls the blood pressure sensor and analyzes signals
measured by the blood pressure sensor to calculate the blood
pressure of the testee at the time of compression and decompression
of the pressure adjusting means.
[0031] FIG. 1 is a graph illustrating the Korotkoff measuring
method in the blood pressure meter according to an exemplary
embodiment of the present invention. The dotted line in FIG. 1
denotes the compressing pressure of the cuff 200a or 200b, the X
axis denotes time, and the Y axis and the solid curve denote the
blood pressure, which indicate the practical pressure in the blood
vessel.
[0032] Supposing that the systolic pressure is 120 mmHg and the
diastolic pressure is 80 mmHg, the blood pressure shown in the Y
axis oscillates between 120 mmHg and 80 mmHg with a period
corresponding to the heartrate. When the compressing pressure of
the cuff 200a or 200b shown by the dotted line is 120 mmHg or more,
the blood flow is blocked and no stethoscopic sound is heard. When
the compressing pressure of the cuff 200a or 200b is decreased and
reaches the vicinity of 120 mmHg, a turbulent flow of blood is
started from the time point a1 to the time point a2, and a
stethoscopic sound is heard. When the compressing pressure of the
cuff 200a or 200b is decreased to the position indicated by a
reference numeral 12 and becomes smaller than 120 mmHg, the
stethoscopic sound becomes distinctly greater from the time point
a3 to the time point a4. When the compressing pressure of the cuff
200a or 200b is decreased to the vicinity of 80 mmHg at the
position indicated by a reference numeral 13, the stethoscopic
sound becomes less from the time point a5 to the time point a6.
When the compressing pressure of the cuff 200a or 200b is further
decreased below 80 mmHg, the blood vessels are completely open and
the turbulent flow, as well as the stethoscopic sound, disappears.
The compressing pressure of the cuff 200a or 200b from the time
point a1 to the time point a2 where the stethoscopic sound starts
is the maximum blood pressure, which is indicated by the reference
numeral 11. A healthy testee has a maximum blood pressure of about
120 mmHg. The compressing pressure of the cuff 200a or 200b from
the time point a5 to the time point a6 where the stethoscopic sound
disappears is the minimum blood pressure, which is indicated by the
reference numeral 13. A healthy testee has a minimum blood pressure
of about 80 mmHg.
[0033] In the Korotkoff measuring method, the stethoscopic sound
starting at the time point when the maximum blood pressure is
measured, and the stethoscopic sound disappearing at the time point
when the minimum blood pressure is measured, are sensed with a
stethoscope. A tester reads out the blood pressure measured by the
blood pressure sensor 600 while hearing the stethoscopic sound with
the stethoscope, and measures the maximum blood pressure and the
minimum blood pressure.
[0034] In an exemplary embodiment of the present invention, a blood
flow sensor 900 senses the blood flow corresponding to the
stethoscopic sound. The control unit 950 controlling the blood flow
sensor 900 and the blood pressure sensor 600 automates the blood
pressure measuring process. An example of the blood flow sensor 900
includes a sound pressure sensor.
[0035] In an exemplary embodiment of the present invention, the
blood flow sensor includes a sound pressure sensor which measures
Korotkoff sounds. The control unit, which controls the blood flow
sensor and the blood pressure sensor and analyzes the signals
measured by the blood flow sensor and the blood pressure sensor to
calculate the blood pressure, calculates the blood pressure using
the Korotkoff measuring method.
[0036] Although not shown in the drawings, the Doppler
ultrasonography measuring method will now also be described. The
phenomenon that a sound frequency increases when the sound source
moves toward an observer, and the sound frequency decreases when
the sound source moves away from the observer, is called the
Doppler effect. The phenomenon occurs in all waves. The phenomenon
can be applied to the medical field for measuring blood flow speed.
An ultrasonic wave is emitted into blood vessels from an emission
unit of an ultrasonic sensor. When the Doppler effect of the
ultrasonic wave reflected by red corpuscles is measured with a
reception unit of the ultrasonic sensor, the blood flow speed can
be obtained. After the blood vessel is blocked by the compression
of the cuff, the cuff is decompressed to allow the blood to start
flowing, and signals due to the Doppler Effect are captured. At
that time point, the blood pressure measured by the blood pressure
sensor is the maximum blood pressure.
[0037] In an embodiment of the present invention, the blood flow
sensor includes an ultrasonic sensor for measuring the Doppler
effect of the ultrasonic wave reflected by the red corpuscles. The
control unit, which controls the blood flow sensor and the blood
pressure sensor, and analyzes the signals measured by the blood
flow sensor and the blood pressure sensor to calculate the blood
pressure, calculates the blood pressure using the Doppler
ultrasonography measuring method.
[0038] FIG. 2 is a graph illustrating the oscillometric measuring
method in the blood pressure meter according to an exemplary
embodiment of the present invention. The uppermost graph indicates
the Korotkoff sound over time. The intermediate graph indicates the
pressure of the cuff 200a or 200b, which is in equilibrium with the
blood pressure. The lowermost graph indicates the amplitude of
vibration of the blood pressure sensor 600.
[0039] In the oscillometric method, the magnitude of pressure
oscillations generated by the cuff 200a or 200b when it is
compressed and then slowly decompressed is sensed by the blood
pressure sensor 600, to measure the blood pressure. The conversion
relationship between the amplitude of vibration as the amplitude of
the pressure oscillation and the blood pressure is calibrated in
advance.
[0040] The oscillometric method is further classified into two
kinds of methods. In the first kind of oscillometric method, the
blood pressure at the time point b1 when the amplitude of vibration
increases rapidly is considered to be the maximum blood pressure,
and the blood pressure at the time point b2 when the amplitude of
vibration decreases rapidly is considered to be the minimum blood
pressure. The systolic pressure is calculated from the amplitude of
vibration Asys measured at the time point b1 and the conversion
relationship between the amplitude of vibration Asys and the blood
pressure. The diastolic pressure is calculated from the amplitude
of vibration Adia measured at the time point b2 and the conversion
relationship between the amplitude of vibration Adia and the blood
pressure.
[0041] In the second kind of oscillometric method, the blood
pressure at the time point when the amplitude of vibration
corresponding to 50% of the maximum amplitude of vibration Amax is
generated is considered to be the systolic pressure, and the blood
pressure at the time point when the amplitude of vibration
corresponding to 75% of the maximum amplitude of vibration Amax is
generated is considered to be the diastolic pressure. Here, 50% and
70% are referred to as characteristic ratios. The characteristic
ratios differ by 10% to 20% between persons.
[0042] The oscillometric measuring method can measure even low
blood pressures at which the Korotkoff sound is not captured,
because heartbeats always cause vibration. In the oscillometric
measuring method, since the amplitude of vibration is measured with
the blood pressure sensor 600, and the maximum blood pressure and
the minimum blood pressure are measured using the characteristic
ratios obtained through clinical experiments, it is possible to
measure the blood pressure even when no blood flow sensor is
provided.
[0043] In an exemplary embodiment of the present invention, the
control unit calculates the blood pressure of the testee by using
the oscillometric measuring method.
[0044] In an exemplary embodiment of the present invention, the
cuff 200a or 200b may be fitted to the wrist, upper arm, finger, or
other body part. When the cuff is fitted in a ring shape to the
finger of a testee, it is very portable.
[0045] When the blood pressure is measured using a finger blood
pressure meter, signals are measured at the artery of the finger
which is thinner than the artery of the upper arm. As a result, the
signal to noise ratio (S/N) is small. Noise due to movement of the
finger has a great influence on the vibration signals of the blood
pressure sensor 600. Since the finger is an extremity of the human
body, the variation in blood pressure and the variation in blood
flow have a close correlation. Therefore, when the cuff 200a or
200b is fitted to a finger, the blood flow sensor 900 may be used
to calculate the blood pressure along with the blood pressure
sensor 600. That is, it is possible to improve the signal to noise
ratio (S/N) of the signal measured by the blood pressure sensor 600
by providing the blood flow sensor 900 along with the blood
pressure sensor 600.
[0046] In an exemplary embodiment of the present invention, the
pressure adjusting means may further include an auxiliary
decompressing means for further enhancing the amount of
decompression of the cuff 200a or 200b due to the viscoelasticity.
The auxiliary decompressing means functions mechanically or
electrically. By utilizing the viscoelasticity of the cuff 200a and
the auxiliary decompressing means, the compressing and
decompressing conditions corresponding to the health condition of
the testee can be prepared. The cuff 200a or 200b according to an
exemplary embodiment of the present invention is smaller than the
conventional air-pressure cuff, but can perform stable
decompression.
[0047] The blood flow sensor 900 is coupled to the cuff 200a or
200b or fitted to the outside thereof. When the blood flow sensor
900 is coupled to the cuff 200a or 200b, the structure of the blood
pressure meter can be simplified. As a result, the blood flow
sensor 900 measuring variation in impedance at the body part fitted
with the cuff 200a or 200b due to variation in blood flow can be
embodied.
[0048] In an exemplary embodiment of the present invention, the
blood flow sensor includes first, second, third, and fourth
terminals sequentially coming contact with the body part in the
blood flow direction. By applying a reference voltage across the
first and fourth terminals and measuring the voltage across the
second and third terminals, it is possible to measure the variation
in impedance at the cuff body part due to the variation in blood
flow.
[0049] In an exemplary embodiment of the present invention, the
control unit checks with the blood pressure sensor whether the
blood flow is impeded at the time of compression of the pressure
adjusting means, captures with the blood pressure at the time point
when the blood flow starts again during the decompression of the
pressure adjusting means, and uses the signal measured by the blood
pressure sensor at the time point when the blood flow starts again
to calculate the systolic pressure.
[0050] Referring to FIG. 9A, when the body part fitted with the
cuff 200a or 200b is a finger, the first, second, third, and fourth
terminals 901, 902, 903, and 904 are provided separately in a ring
shape around the finger. The reference voltage Vcc is applied
across the first terminal 901 and the fourth terminal 904. The
variation in blood flow varies the impedance of the finger. The
variation in impedance is measured as the voltage Vi across the
second terminal 902 and the third terminal 903.
[0051] Referring to FIG. 9B, the cuff 200a or 200b fitted with the
blood flow sensor 900 is shown partially exploded. The blood flow
sensor 900 is attached to the cuff 200a or 200b. The blood flow
sensor 900 includes the first, second, third, and fourth terminals
901, 902, 903, and 904. The blood pressure sensor 600 is provided
on the blood flow sensor 900.
[0052] FIG. 9C shows the voltage Vi across the second terminal 902
and the third terminal 903 due to pulsation of the blood flow. The
blood flow sensor 900 is not limited to the type shown, and may be
embodied in various ways to measure impedance.
[0053] Now, the viscoelasticity of the cuff 200a or 200b according
to the exemplary embodiment of the present invention will be
described.
[0054] An elastic solid quickly returns to its initial state in
accordance with Hooke's Law, when the external force resulting in
the deformation is removed. However, a polymer compound or a
poly-crystalline body returns more slowly to its initial state.
This is because of a viscoelastic behavior, involving both
elasticity and viscosity. The viscoelastic behavior is expressed in
a dynamic model in which a spring and a damper are combined.
Dynamic models are classified into a Voigt model in which the
spring and the damper are combined in parallel, and a Maxwell model
in which the spring and the damper are combined in series.
[0055] An example of the viscoelastic cuff is "VHB tape" made by 3M
Co.
[0056] FIG. 3A is a graph obtained by applying load to a
viscoelastic material to expand it, and measuring the variation in
load over time while maintaining a constant deformation. FIG. 3A
shows the elasticity of the cuff 200a or 200b, in which the load is
increased in proportion to the elastic deformation from the initial
time to the time point indicated by a reference numeral 31. The
load is decreased by .DELTA.L over time even when the elastic
deformation of the cuff 200a or 200b is maintained after the time
point 31. The compressing pressure acts up to the time point 31
with the elasticity of the cuff 200a or 200b. Thereafter, the load
is decreased by .DELTA.L after a time .DELTA.T with the viscosity
of the cuff 200a or 200b. The compressing pressure indicated by a
reference numeral 32 remains in the body part fitted with the cuff
200a or 200b.
[0057] FIG. 3B is a graph illustrating the viscoelastic behavior of
the cuff 200a or 200b when the auxiliary decompressing means
according to an exemplary embodiment of the present invention is
provided. The body part is compressed with the compressing pressure
indicated by a reference numeral 35 with the elasticity of the cuff
200a or 200b. Thereafter, the body part is decompressed by
.DELTA.L1 only due to the viscosity of the cuff 200a or 200b. When
the auxiliary decompressing means is provided along with the cuff
200a or 200b, the amount of decompression is increased to
.DELTA.L2.
[0058] FIG. 4A is a perspective view illustrating the cuff 200a in
the blood pressure meter according to an exemplary embodiment of
the present invention before fitting the cuff 200a. FIG. 4B is a
plan view illustrating the cuff 200a after fitting the cuff
200a.
[0059] In an exemplary embodiment of the present invention, the
pressure adjusting means includes a cuff fitting member having
first and second pieces of which both ends of the cuff are fixed
and lockers are provided at one ends, of which the other ends are
coupled to each other with a hinge member.
[0060] At the time of fitting the cuff, the first and second pieces
are locked to each other through the lockers. At the time of
removing the cuff, the first and second pieces are unlocked and
opened about the hinge member.
[0061] The cuff fitting member 400a includes a pair of semicircular
rings having the first and second pieces 401 and 402. The first and
second pieces 401 and 402 are rotatably coupled to each other
through the hinge member 405. The cuff 200a is made of a
viscoelastic material in a band shape. The ends of the cuff 200a
are fixed respectively to the ends of the first and second pieces
401 and 402. When the cuff 200a is fitted to the testee, the first
and second pieces 401 and 402 are rotated about the hinge member
405. The rotation of the first and second pieces 401 and 402
applies tension to expand the cuff 200a. The expanded cuff 200a
comes in contact with the body part of the testee and the first and
second pieces 401 and 402 are rotated in the locking direction. The
ends of the first and second pieces 401 and 402 are provided with
the locker 406, which locks the rotation of the cuff fitting member
400a. The expanded cuff 200a can easily surround the body part, and
generates the compressing pressure with its elastic restoring
force, thereby impeding the blood flow. When the cuff 200a is
fitted on a finger, the finger is positioned inside the cuff 200a
shown in FIG. 4B. The blood pressure sensor 600 is interposed
between the cuff 200a and the finger to measure the blood pressure.
The blood flow sensor 900 is interposed between the cuff 200a and
the finger to sense the blood flow. The body part is decompressed
over time due to the viscoelasticity of the cuff 200a, and thus the
blood begins to flow again. When the blood flow sensor 900 senses
the blood flow resuming, the control unit 950 receives the signal
measured by the blood pressure sensor 600 and calculates the
maximum blood pressure. The blood pressure may be measured using
any one of the above-mentioned methods.
[0062] The pressure adjusting means may further include an
auxiliary decompressing means. As an example of the auxiliary
decompressing means, a cuff interference member is provided in the
cuff fitting member.
[0063] In an exemplary embodiment of the present invention, the
pressure adjusting means further includes a cuff interference
member that is rotatably provided in the cuff fitting member. The
cuff interference member contacts and interferes with the cuff in
the direction in which the cuff comes in close contact with the
body part at the initial time of fitting the cuff, and then is
rotated in the opposite direction over time. The cuff interference
member further enhances the amount of decompression of the cuff due
to the viscoelasticity.
[0064] In an exemplary embodiment of the present invention, the
pressure adjusting means further includes a cuff interference
member that is slidably provided in the cuff fitting member. The
cuff interference member contacts and interferes with the cuff in
the direction in which the cuff comes in close contact with the
body part at the initial time of fitting the time, and then slides
in the opposite direction over time. The cuff interference member
further enhances the amount of decompression of the cuff due to the
viscoelasticity.
[0065] FIGS. 5A and 6A are plan views illustrating the auxiliary
decompressing means according to an exemplary embodiment of the
present invention before fitting the cuff 200a, and FIGS. 5B and 6B
are plan views illustrating the auxiliary decompressing means after
fitting the cuff 200a. FIGS. 5A and 5B show the cuff interference
member 250a rotatably coupled to the cuff fitting member 400a, and
FIGS. 6A and 6B show the cuff interference member 250b slidably
coupled to the cuff fitting member 400a. The reference numeral 200a
denotes a cuff composed of one band and the reference numerals 200b
denotes a cuff composed of a pair of bands. Like reference numerals
denote like elements, and thus their description will not be
repeated.
[0066] The cuff interference member 250a or 250b contacts and
interferes with the cuff 200a or 200b to provide a compressing
pressure at the initial time of fitting. The cuff interference
member 250a or 250b is then rotated or slid over time, and performs
the mechanical decompressing function in addition to the
decompressing function due to the viscoelasticity of the cuff 200a
or 200b.
[0067] The pressure adjusting means according to an exemplary
embodiment of the present invention may further include an
auxiliary decompressing means. As an example of the auxiliary
decompressing means, a cuff hole and a cuff cam are provided in the
cuff fitting member.
[0068] In an exemplary embodiment of the present invention, the
cuff is composed of a pair of bands, with one end fixed
respectively to the first and second pieces, and the other ends
free. Here, the pressure adjusting means further includes a cuff
hole formed in the hinge member so as to pass the free ends; and a
cuff cam formed in the hinge member so as to compress the free ends
when the first and second pieces are unlocked and to release the
free ends when the first and second pieces are locked. The cuff
hole and the cuff cam further enhance the amount of decompression
of the cuff due to its viscoelasticity.
[0069] FIG. 7A is a plan view illustrating a state before fitting
the cuff 200b, and FIG. 7B is a plan view illustrating a state
after fitting the cuff 200b. The cuff 200b denoted by the reference
numeral 200b in FIGS. 7A and 7B is composed of a pair of bands,
with one end fixed respectively to the ends of the first and second
pieces 401 and 402, and the other end free. Before fitting the cuff
200b, the free end 201 is pulled and a tension is applied to the
cuff 200b at the portion from the hinge member 405 to the ends of
the first and second pieces 401 and 402. The cuff cam 310 has a D
shape in which a part of an ellipse is cut out, and includes a
convex portion and a concave portion. The free ends 201 pass
through the cuff hole 300.
[0070] Before fitting the cuff 200b, the first and second pieces
401 and 402 are not locked, and the free ends 201 are pressed
toward the cuff hole 300 by the convex portion of the cuff cam 310.
The cuff 200b, of which the free ends 201 are compressed, is
restricted and expanded as it comes in contact with the body part
fitted with the cuff 200b.
[0071] When the first and second pieces 401 and 402 are rotated in
the locking direction at the same time as fitting the cuff 200b,
the cuff 200b surrounds and compresses the body part. When the
first and second pieces 401 and 402 are locked, the concave portion
of the cuff cam 310 releases the free ends 201. Accordingly,
mechanical decompression is performed in addition to the
decompression due to the viscoelasticity of the cuff 200b.
[0072] The pressure adjusting means according to the present
invention further includes an auxiliary decompressing means. A cuff
driving unit is provided as an example of the auxiliary
decompressing means.
[0073] In an exemplary embodiment of the present invention, the
cuff is composed of a pair of bands with one end of each free, and
the pressure adjusting means further includes a cuff fitting member
fixing the other end of the cuff, and a cuff driving unit that
pulls the free end so as to compress the body part fitted with the
cuff at the initial time of fitting the cuff and then gradually
release it over time, so as to further enhance the amount of
decompression of the cuff due to the viscoelasticity.
[0074] Here, the cuff driving unit may include a cuff driving axis
around which the free end of the cuff is wound, and the cuff
driving unit adjusts the compressing pressure and the decompressing
pressure by rotating the cuff driving axis.
[0075] FIG. 8 is a plan view illustrating an exemplary embodiment
of the cuff driving unit according to the present invention. The
cuff fitting member 400b shown in FIG. 8 has a circular ring shape,
but is not limited to this embodiment, and may be divided into the
first and second pieces 401 and 402. The free end 201 of the cuff
200b is wound around the cuff driving axis 810. The cuff driving
unit 800 rotates the cuff driving axis 810 under the control of the
control unit 950 to adjust the amount of compression and
decompression in response to the signals measured by the blood
pressure sensor 600 and the blood flow sensor 900.
[0076] FIG. 10 is a block diagram illustrating a mobile terminal
having the blood pressure meter according to an exemplary
embodiment of the present invention. FIG. 11 is a perspective view
illustrating an example where a testee measures their blood
pressure with the mobile terminal having the blood pressure meter.
The mobile terminal having the blood pressure meter includes a
mobile terminal body 999 and a blood pressure measuring unit 930.
The mobile terminal body 999 includes a display unit 980 for
displaying the measured blood pressure. The blood pressure
measuring unit 930 is connected to the mobile terminal body 999.
The blood pressure measuring unit 930 includes the pressure
adjusting means 920, the blood pressure sensor 600, and the blood
flow sensor 900. The pressure adjusting means includes the cuff
200a or 200b and the cuff fitting member 400a or 400b. The pressure
adjusting means may further include the auxiliary decompressing
means.
[0077] The control unit 950 may be provided in the blood pressure
measuring unit 930 or the mobile terminal body 999. In FIG. 10, the
control unit 950 is provided in the mobile terminal body 999. The
mobile terminal body 999 may further include a storage unit 960, an
input unit 970, and a display unit 980. The blood pressure
measuring unit 930 may be detachably connected to the mobile
terminal body 999. An element 998 connecting the blood pressure
measuring unit 930 and the mobile terminal body 999 denotes a wired
connection means or a wireless communication means using infrared
rays. The wireless communication means is well known to those
skilled in the art and thus a description thereof will be
omitted.
[0078] When a testee inputs information necessary for measuring
their blood pressure to the input unit 970, the input information
is displayed on the display unit 980 and stored in the storage unit
960. For example, measuring time, nothing of repeated measurement,
and repeated measurement periods are input. The control unit 950
controls the blood pressure meter in accordance with the
information stored in the storage unit 960. The control unit 950
calculates the maximum blood pressure and the minimum blood
pressure from the signals measured by the blood pressure sensor 600
and the blood flow sensor 900. The calculated blood pressure is
stored in the storage unit 960 and output to the display unit
980.
[0079] Examples of the mobile terminal body 999 may include a
mobile phone, a portable computer, and a wristwatch. The blood
pressure measuring unit 930 can be attached to and detached from
the mobile terminal body 999 at any time. The testee can easily
measure their blood pressure at any time to manage their
health.
[0080] An example of the application of the mobile terminal having
the blood pressure meter according to an exemplary embodiment of
the present invention will now be described. At a certain time
every day, the control unit 950 informs the testee that it is time
to measure their blood pressure. The testee fits the cuff 200a or
200b to their finger and connects the blood pressure measuring unit
930 to the mobile terminal body 999. The control unit 950 controls
the blood pressure sensor 600 and the blood flow sensor 900 to
calculate the blood pressure in accordance with the measured
signals. The calculated blood pressure is stored in the storage
unit 960. The blood pressure stored in the storage unit 960 can be
cumulatively managed, thereby checking the testee's health
condition. When the mobile terminal body 999 has a communication
function, the measured blood pressure can be transmitted to a
doctor or a health management server, the health condition can be
checked, and the result can be returned to the testee.
[0081] As described above, in the blood pressure meter and the
mobile terminal having the blood pressure meter according to an
exemplary embodiment of the present invention, since the blood
pressure is measured with the cuff made of a viscoelastic material
instead of the conventional air-pressure cuff, it is possible to
decrease the size of the blood pressure meter, to improve the
portability. In addition, since the cuff can be decreased in size
while maintaining the signal-to-noise ratio, it is possible to
accurately measure the blood pressure with the cuff fitted to a
finger. The reliability in measuring the blood pressure can be
improved by providing the blood flow sensor, and desired
compression and decompression conditions corresponding to the
health condition of the testee can be prepared by utilizing the
viscoelasticity of the cuff and the auxiliary decompressing means.
Since the mobile terminal body and the blood pressure measuring
unit can be detachably connected, the blood pressure can be
measured at any time.
[0082] While the present invention has been particularly shown and
described with reference to exemplary embodiments thereof, it will
be understood by those skilled in the art that various changes in
form and details may be made therein without departing from the
spirit and scope of the present invention as defined by the
appended claims.
* * * * *